The present invention generally relates to electric lighting fixtures, and more particularly to mounting hardware for securing ballasts within the housing of a fluorescent lighting fixture. The invention has particular application in linear indirect lighting fixtures having limited space for mounting a ballast.
Linear fluorescent lighting, which is widely used in offices and other commercial environments, employ ballasts of standard configurations and sizes supplied by a ballast manufacturer. The ballasts normally are provided with mounting flanges that have longitudinal mounting slots for attaching the ballast to the lighting fixture housing, for example, to T-slots extruded into the bottom of the housing. However, space constraints often make this mounting arrangement difficult. For example, in a six-inch round linear indirect fixture, which is a commonly used shape, the side edges of the base of the ballast will often hit the inner cylindrical walls of the fixture housing before the ballast is able to seat against the bottom of the housing. This causes the fixture to ride higher up in the housing and interfere with the fixture's reflector which is mounted over the ballast. To solve this problem, the ballast is frequently inverted such that the narrower top end of the ballast will fit further down into the housing. Heretofore, when such an inverted mounting position has been used, the ballast normally has been held down by a separate metal strap. (This is due to the unavailability of the now inverted ballast mounting flanges.)
The difficulty with using metal straps is that such straps must be pre-formed to fit a ballast of a particular height and length. This increases the number of parts needed for the manufacture of fixtures carrying different ballast sizes. Also, where spaces are confined, the fixture's reflector may contact the top of the ballast and such contact will tend to distort the reflector which optically is undesirable. The strap across the ballast acts to amplify this distortion. A further problem with using a conventional strap is that the ballast also tends to shift underneath the strap during shipment of the lighting fixtures which creates a risk that the ballast will come loose.
Another heretofore known approach to mounting the ballast in an inverted position is to use two partial straps at the end of the ballast. While the partial straps could be adapted to any length of ballast, it could not be adapted to any height. Such straps are also not very strong and create an even greater risk that the ballast will shift in the housing and come loose.
The invention overcomes the above-mentioned drawbacks associated with straps and partial straps for mounting ballast in an inverted position within a lighting fixture housing. The invention provides for a ballast holder which affixes to the ends of the ballast only, which is very stiff so as to prevent shifting and which will accommodate any standard ballast size. Further, the ballast holder of the invention is easy to install and can be inexpensively fabricated from a piece of stamped sheet metal.